Shipping an item by mail or courier? Worried about the weight? Guess what, the volume of your package is just as important, maybe more so. This is especially true if your package is fairly low density (light weight for it's size).
Most shippers will determine both the weight and the linear dimensions of your pakage. They then use these measurements in a formula to determine your overall cost. Shipping a big box full of popcorn may cost you the same as shipping a small box of nuts and bolts.